Recycling is confusing, even for the most well-intentioned and informed conscious consumers. Capabilities of municipal recycling facilities vary from region to region, and items that are difficult-to-recycle sometimes get looped in with regularly accepted items.

Not all paper, metal, glass and plastic packaging is created equal, and many common items that seem to fall in the “recyclable” category are far from it. Knowing to “watch out” for these common household waste items will help you prevent contamination at your local municipal recycling facility (MRF) and ensure that the items you do recycle are kept at their highest value at all times:

1. Black plasticPlastic is plastic, right? With regards to the types of plastic accepted curbside in general, we know this to be vastly untrue, but black plastic is a big recycling “watch out” that many people are unaware of. The optical scanners used to identify types of plastic at municipal recycling facilities using the reflection of light deem black plastic unrecyclable in the current infrastructure. Why? Black plastic does not reflect light. Thus, the rigid plastic of black microwave food trays, takeout containers and other items are not accepted by most MRFs, even if the resin number on the bottom is accepted in your bin.

2. Gradient glassGlass is one of the most highly recyclable materials accepted by MRFs, but depending on where you live, some curbside programs require residents to sort colored glass from clear glass, or only accept clear and brown (both of which generally have high market demand). Once colored, glass cannot be turned into another color, so when it comes to gradient or multi-colored glass, the material is not recyclable because these colors cannot be separated.

When contaminants (i.e. different color glass or other materials) are mixed in with glass, it decreases the value of the recovered glass, increases costs and slows production. Gradient and multi-colored glass, then, is basically a contaminant to itself in the current recycling infrastructure. But on the up side, this discarded glass, if captured, is often milled and ground for use in concrete.

Ed.: While the original article states with regards to the PlantBottle, a durable bioplastic alternative to traditional PET bottles made by Coca-Cola, that it can be recycled with traditional PET containers and bottles, I have expressly told by several waste management companies, and not just in the UK, that this is NOT the case.